JPH06149033A - Developing device - Google Patents

Abstract

PURPOSE:To stop developer from retaining in the vicinity of the exit of a developer flow passage, to prevent developer supply defect such as developer clogging, etc., in the developer flow passage and to maintain the constant supply quantity of the developer to a latent image carrier by a developer carrier. CONSTITUTION:A plate-like flow straighting plate 8 forming the developer flow passage 9 together with a supply roller 4 is disposed above the supply roller 4. Then the flow straighting plate 8 is disposed in a state where an angle theta1 is formed against a horizontal line L2 as indicated by a straight line L1 in parallel with its lower surface and a tip part 81 is lower than a trailing end part 82. Also the flow straighting plate 8 is disposed so that it may be bent upward, i.e., on a downstream side in the rotation direction of a developing roller 3 at a bending part in the vicinity of the tip part 81, and it may form the angle theta2 against the straight line L1 as indicated by the straight line L3 in parallel with the lower surface, and the tip part 81 may be upper than the bending part 83.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for an image forming apparatus such as a copying machine, a facsimile machine, a printer, etc., and more specifically, a developing device capable of effectively supplying a developer from a developer supplying member to a developer carrier. It is about.

[0002]

2. Description of the Related Art Conventionally, for example, a developer carried from a developer container by a carrying member provided in a developer container is carried by a developer supplying member provided in the developer container. After being supplied to the body and scraped off the excess developer of the developer adhered to the developer carrier by the developer regulating member, the developer on the developer carrier is made to have a predetermined thickness,
There is known a developing device that supplies the developer to the latent image formed on the surface of the latent image carrier to develop the latent image. Further, in the developing device, the developer carrying member is, for example, a rotatable drive roller, and has a peripheral length slightly longer than the peripheral length of the drive roller and is mounted on the drive roller, and at least a part of the surface. Is also known (for example, Japanese Unexamined Patent Publication No.
257981 and Japanese Patent Laid-Open No. 1-257982).

Here, the developer supply member and the developer carrier are among the developers supplied from the developer container.
Since the developer carried in contact with the rough surface portion formed on those surfaces is carried, a large amount of developer cannot be carried, and the developer carrying amount is limited. Therefore, if the developer carrying ability of the carrying member, the developer supplying member, and the developer carrying body is constant, for example, if high-concentration development continues, the developer on the developer carrying body is almost consumed in the first development. However, in the subsequent development, there is a problem that the amount of developer supplied by the developer carrying member (the amount of developer held on the developer carrying member) becomes insufficient and the density may decrease.

Therefore, in order to solve this problem, it has been proposed to supply the developer by applying a certain pressure to the developer carrier. Specifically, a developer rectifying member is fixedly arranged above the developer supply member, and a developer flow path is formed by the developer rectifying member and the developer supply member, and from the inside of the developer container. A developing device has been proposed in which, when the conveyed developer passes through the developer flow path, the developer rectifying member applies pressure to the developer and supplies the developer to a developer carrier (for example, Kaihei 4-57080
(See Japanese Patent Publication).

[0005]

However, depending on the arrangement and the specific shape of each member in the developing device disclosed in Japanese Patent Laid-Open No. 4-57080, the developing process is performed by applying a certain amount of pressure by the developer rectifying member. The developer easily stays near the outlet of the developer flow path, the flow of the developer is not stable due to the rotation of the developer carrier, and as a result, the developer supplied to the latent image carrier by the developer carrier. It was confirmed that the dose could not be kept constant. Also,
It was confirmed that when there is no flow of the developer during non-development, the developer is packed by the pressure of the developer rectifying member, and the developer may be clogged in the developer flow path.

The present invention has been made in view of the above problems. A first object of the present invention is to supply a developer to a developer carrying member by applying an appropriate pressure to the developer. By stabilizing the flow of the developer due to the rotation of the developer carrier without allowing the developer to stay near the outlet of the developer channel,
It is an object of the present invention to provide a developing device capable of keeping the amount of developer supplied to the latent image carrier by the developer carrier constant. In addition to the first purpose, the second purpose is to prevent developer supply failure such as developer clogging in the developer flow path and to obtain stable and good developer supply performance. It is to provide a developing device capable of performing.

[0007]

In order to achieve the first object, the invention of claim 1 is a developer carrier for supplying a developer to a latent image carrier having a latent image formed on the surface thereof. , A developer supply member for supplying the developer to the developer carrier, and a developer supply member facing the developer supply member with a space therebetween, and developing on the developer carrier at a portion facing the developer supply member. In a developing device provided with a developer rectifying member that forms a developer flow path, an end portion of the developer rectifying member near the developer carrier is rotated between the developer carrier and the developer carrier. It is characterized in that the developer is guided to the downstream side in the direction. Further, in order to achieve the second object, the claim 2
The invention of claim 1 is characterized in that, in the developing device according to claim 1, the developer rectifying member can be separated from the developer supplying member so as to reduce the pressing force against the developer during non-developing. To do. Further, in order to achieve the first object, the invention of claim 3 is the developing device of claim 1, wherein at least the portion near the developer carrying member of the developer rectifying member is made of a conductor, and The developer rectifying member, the developer carrying member, and the developer supplying member are arranged so as to form a predetermined gap, and between the developer rectifying member and the developer carrying member, and the developer. A voltage is applied to at least one of the rectifying member and the developer supplying member to form an electric field whose intensity changes periodically at least.

[0008]

According to the invention of claim 1, the developer having passed through the developer flow path is guided to the downstream side in the rotation direction of the developer carrying member along the end of the developer rectifying member in the vicinity of the developer carrying member, It is supplied to the developer carrier. In the invention of claim 2, the developer remaining in the developer flow path at the time of non-development is released from the pressed state by the developer rectifying member and the developer supply member. According to the third aspect of the invention, an electric field whose strength changes periodically is formed at least between the developer rectifying member and the developer carrier and between the developer rectifying member and the developer supplying member. Therefore, the developer vibrates at least one of between the developer rectifying member and the developer carrying member or between the developer rectifying member and the developer supplying member, and the fluidity is enhanced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a developing device used in a copying machine according to this embodiment. In the developing device 1, the photosensitive drum 2 as a latent image carrier is provided in the opening 2.
In order to develop the latent image formed on the 0 surface, a developing roller 3 is provided as a developer bearing member that faces the photosensitive drum 20 and is rotatably supported. At the bottom of the casing of the developing device 1, there is provided a supply roller 4 as a developer supply member for supplying a developer to the developing roller 3, which is rotatably supported at a predetermined distance from the developing roller 3. Has been. An agitator configured to be rotatable around a shaft 61 in the developer accommodating portion 5 for supplying the developer (not shown) accommodated in the developer accommodating portion 5 to the supply roller 4. 6 is provided.

Further, in the developing device 1 shown in the figure, excess developer of the developer adhering to the surface of the developing roller 3 is scraped off to form a thin layer of the developer on the surface of the developing roller 3, and at the same time, the developing roller 3 A developer regulating member 7 for frictionally charging the developer adhered to is provided, and the developer regulating member 7 and a casing forming the bottom of the developing device 1 form an opening 2.

Above the supply roller 4, a plate-like member serving as a developer rectifying member that forms a developer flow path 9 for the developer conveyed by the agitator 6 to the developing roller 3 together with the supply roller 4. A current plate 8 is provided. As shown by a straight line L1 parallel to the lower surface of the straightening plate 8 in the drawing, an angle θ1 is formed with respect to the horizontal line L2, and the developing roller 3 side end portion (hereinafter, referred to as the leading end portion) 81 has an agitator 6 side end. It is arranged so as to be in a state of being lowered from a portion (hereinafter, referred to as a rear end portion) 82. Further, the straightening plate 8 is bent upward at the bent portion 83 near the tip 81, that is, on the downstream side in the rotation direction of the developing roller 3, and as shown by a straight line L3 parallel to the lower surface thereof, with respect to the straight line L1. To form an angle θ2 so that the tip 81 is raised above the bent portion 83. With the above-described configuration, the developer flow passage 9 generally has a wide opening at the developer inlet, becomes narrower as it approaches the bent portion 83, and becomes wider again as it approaches the developer outlet from the bent portion 83. Has been formed.

In the above structure, the developer is conveyed from the developer accommodating portion 5 toward the supply roller 4 when the agitator 6 rotates about the shaft 61 in the arrow direction. Then, the developer is supplied to the developing roller 3 through a developer flow passage 9 formed by the flow straightening plate 8 and the supply roller 4. The developer supplied to the developing roller 3 and attached to the surface of the developing roller 3 electrically (or magnetically or physically), for example, is rotated by the developing roller 3 in the direction of the arrow so that the developer regulating member 7 causes the developing roller to rotate. 3 The surface is scraped, leaving a predetermined amount. At this time, the developer remaining on the surface of the developing roller 3 is
The photoconductor drum 2 is frictionally charged by the developer regulating member 7.
In the developing area where 0 and the developing roller 3 are opposed to each other and the developing is performed, the latent image is developed by adhering to the latent image formed on the surface of the photoconductor drum 20. Further, the developer that could not pass through the developer regulating member 7 returns to the inside of the developing device 1 and the above operation is repeated.

Next, the flow of the developer to the developing roller 3 will be described. As the developer conveyed by the agitator 6 passes through the developer flow path 9,
The developing roller 3 while being compressed from above by the current plate 8.
Is conveyed in the direction. Then, the developer that has passed through the bent portion 83 is guided to the downstream side in the rotation direction of the developing roller 3 along the straightening plate 8 at the outlet of the developer flow path 9 and adheres to the surface of the rotating developing roller 3.

Further, in this embodiment, the straightening plate 8 is used.
Is movable. For example, the rear end portion 82 of the flow straightening plate 8 is rotatably supported, and the front end portion 81 side is vertically movable by using an actuator such as a solenoid. The current plate 8 is in the state shown in FIG. 2A during development, that is, when the developer is flowing through the developer flow path 9, and is suitable for the developer passing through the developer flow path 9. Applying a great pressure. Further, the current plate 8 is used for non-development such as when the operation of the copying machine is stopped, that is, the developer flow path 9
When the developer inside does not flow, as shown in FIG. 2B, the front end portion 81 side moves upward with the rear end portion 82 as an axis so as to form an angle θ3 with respect to the state of FIG. 2A. By widening the developer channel 9 and the vicinity of the outlet of the developer channel 9, the pressure on the developer existing in the developer channel 9 and in the vicinity of the outlet of the developer channel 9 is weakened.

According to the above structure, the developer does not stay near the outlet of the developer flow path 9 even if an appropriate pressure is applied by the straightening plate 8 during development, and the developer flows stably. Is supplied to the developing roller 3, and at the time of non-development, the developer channel 9 or the developer clogging (blocking phenomenon) in the vicinity of the developer outlet of the developer channel 9 does not occur.

In the experiments conducted by the present inventor in the above embodiments, the developing roller 3 is, for example, Al sandblasted to have a surface roughness Rz of about 5 μm, or carbon black or copper particles are dispersed on the surface. The acrylic resin, Teflon resin, or Si resin thus coated was used in an amount of about 10 to 500 μm. As the supply roller 4, for example, a foam sponge roll or a surface-roughened Al or SUS-based material is used. As the developer, for example, a mixture of styrene-acryl or polyester having a pellet resistance of 10 ¹⁰ Ωcm or more and a relative dielectric constant of 4 or less was used. As the third additive, for example, SiO ₂ , TiO ₂ , SiC, or zinc stearate was used, and this was mixed with the base material in an amount of 0.1 to 1.0 wt%. In particular, SiO ₂ has a particle size of about 80 nm to 1 μm and uses hydrophobic silica. Further, the gap between the developing roller 3 and the supply roller 4 is set to, for example, 0.05 to 1 mm. Further, the gap between the current plate 8 and the developing roller 3 or the supply roller 4 is set to, for example, 1 mm or less at the closest portion. The current plate 8 is, for example, an Al or SUS plate and is formed to have a thickness of 0.5 mm or more. Further, the angles θ1, θ2, and θ3 are, for example, the angle θ1.
Is set to 10 to 30 °, the angle θ2 is set to 20 to 50 °, and the angle θ3 is set to 10 ° or more. Further, the supply roller 4 is
In the area facing the developing roller 3, the developing roller 3 was rotated in the swirl direction (clockwise direction in FIGS. 1 and 2) with respect to the rotation direction (counterclockwise direction in FIGS. 1 and 2). When an experiment was conducted under the above conditions, the supply performance of the developer to the developing roller 3 could be maintained well.

Next, an embodiment for efficiently flowing the developer in the developer channel 9 and in the vicinity of the outlet of the developer channel 9 will be described with reference to FIG. In FIG.
The developing roller 3 is applied by the voltage (V _R) is a power supply 30 having a DC component. Further, the voltage (V _B ) having a DC component is also applied by the power supply 31 to the supply roller 4 arranged with a predetermined gap with respect to the developing roller 3. The rectifying plate 8 arranged with a predetermined gap between the developing roller 3 and the supply roller 4 has a DC component (V
A voltage having an _S ) and an AC component (V _PP ) is applied by the power supply 32.

In the above structure, between the straightening plate 8 and the developing roller 3 and between the straightening plate 8 and the supply roller 4,
An electric field is formed by the voltage applied to each. Then, the developer receives an electrostatic force due to this electric field. Here, since the voltage applied to the rectifying plate 8 has an AC component, it is between the rectifying plate 8 and the developing roller 3 and between the rectifying plate 8 and the developing roller 3.
At least the strength of the electric field formed between the supply roller 4 and the supply roller 4 changes due to the AC component. As a result, the developer oscillates while being passed between the flow straightening plate 8 and the developing roller 3 and between the flow straightening plate 8 and the supply roller 4 by being subjected to an electrostatic force whose strength changes at least due to the AC component. .

As described above, according to this embodiment, as described above, the developing roller 3, the supply roller 4, and the rectifying plate 8 are arranged at a predetermined interval, and between the rectifying plate 8 and the developing roller 3, Also, since the developer in the developer channel 9 or in the vicinity of the outlet of the developer channel 9 can be vibrated by the electric field that periodically changes the direction between the rectifying plate 8 and the supply roller 4, the developer stays. It is possible to efficiently flow without doing so and to smoothly supply the developer to the developing roller 3. Further, since the developer vibrates between the flow straightening plate 8 and the developing roller 3 and between the flow straightening plate 8 and the supply roller 4, the developer is frictionally charged between the developing roller 3 and the supply roller 4, As a result, the charge amount of the developer can be increased.

In the experiments conducted by the inventor of the above embodiment, in addition to the experimental conditions relating to the embodiments of FIGS. 1 and 2, the voltage of the power supply 32 is, for example, between the straightening plate 8 and the developing roller 3. , And the voltage (V _S ) of the DC component in the range of 10 ⁵ to 10 ⁷ V / m as the electric field between the rectifying plate 8 and the supply roller 4, and the voltage of the AC component (Equation 1) When _VPP ) was used, complete developer flow could be confirmed. When the voltage (V _PP ) of the AC component that satisfies the expression without the equal sign among the following formulas is used, the direction of the electric field changes according to the cycle of the AC component, and the rectifying plate 8
By causing the reciprocating motion of the developer between the developing roller 3 and the developing roller 3, and between the rectifying plate 8 and the supply roller 4, the fluidity of the developer can be further enhanced.

[Equation 1]

Further, in this embodiment, in order to form a predetermined electric field between the rectifying plate 8 and the developing roller 3 and between the rectifying plate 8 and the supply roller 4, a voltage having an AC component is applied to the rectifying plate 8. Instead of this, a voltage having an AC component is applied to the developing roller 3 between the rectifying plate 8 and the developing roller 3, and a voltage between the rectifying plate 8 and the supplying roller 4 is applied to the supplying roller 4. A voltage having an AC component may be applied. In these cases, the rectifying plate 8 may be applied with a voltage having only a DC component or may be grounded.

By the way, in general, the developer is consumed relatively little at both ends in the axial direction of the developing roller 3, and the developer carried in this portion stays in the developing device 1 for a long period of time, and the developer and the developing agent are in contact with each other. Due to friction with the surface of the roller 3 or the like, the particle size becomes relatively small by pulverization, and the additive (third additive) is buried in the surface, so that the fluidity and the charging property are deteriorated and a so-called dead toner is formed. Become. Then, such dead toner accumulates in the gap between the both ends of the developing roller 3 in the axial direction and the rectifying plate 8 (so-called bridge formation), which may cause developer supply failure or adhere to the surface of the photosensitive drum 20. Then, it may cause dirt. Therefore, in the following, the rectifying plates 8 corresponding to both axial end portions of the developing roller 3 will be described.
An example for preventing the retention of the developer at the both side end portions will be described. FIG. 4A is an explanatory view of the current plate 8a according to the present embodiment, which is arranged near the developing roller 3 and the supply roller 4, and is viewed from the inlet side of the developer flow path 9. 4 (b) is a sectional view taken along line XX in FIG. 4 (a). The rectifying plate 8a has a side end portion 84,
As indicated by a straight line L4 parallel to the lower surface thereof, it is bent upward at the bent portion 85, that is, to the downstream side in the rotation direction of the developing roller 3 so as to form an angle θ4 with respect to the straight line L5 parallel to the lower surface of the straightening plate 8a. There is. With the above configuration, the developer flow passage 9 is formed so that both sides in the axial direction of the supply roller 4 (or the developing roller 3) are wide.

In the above structure, the developer compressed from above by the flow straightening plate 8a when passing through the developer flow path 9 has a flow toward the side end portion 84 side of the flow straightening plate 8a having a weak compression force. . As a result, the circulation of the developer in the width direction of the developer flow path 9 (the axial direction of the supply roller 4 (or the developing roller 3)) is improved, and the generation of the dead toner can be prevented. Can be prevented. Further, since the developer can be uniformly distributed in the width direction of the developer flow path 9, it is possible to stably supply the developer.

According to the experiments conducted by the present inventor regarding the above-mentioned embodiment, the result that the angle θ4 needs to be set to 5 ° or more and is preferably 60 ° or less is obtained.

In the embodiment described above,
When the developer supply amount to the developing roller 3 cannot catch up, for example, when the photosensitive member linear velocity is high and the developer supply amount is insufficient, the rotating member 4a having a square cross-section as shown in FIG. It can be used as a supply member. When such a rotating body 4a is used, when the rotating body 4a rotates, the distance between the developing roller 3 and the rectifying plate 8 changes, so that the developer carrying ability and the pressure contact force with respect to the developing roller 3 are strengthened. It is possible to secure a stable and sufficient developer supply amount.

According to an experiment conducted by the inventor of the above embodiment, one side of the rotating body 4a is 5 mm or more, and the rotating body 4a is arranged so that the distance of the closest portion to the current plate 8 is 300 μm or less. The peripheral speed ratio between the rotating body 4a and the developing roller 3 is preferably 0.3 or more and 2 or less, and the diameter of the rotating body 4a and the developing roller 3 (diagonal line in cross section when the rotating body 4a has a square cross section, for example). The result is that the ratio of (length) should be 0.3 or more. Under the above conditions, it was possible to obtain an image with sufficient density up to the linear velocity of the photosensitive drum 20 of 20 to 180 mm / s.

In the embodiment described above, the tip portion 8
Although the straightening plate 8 of FIG. 1 is used, a straightening plate 8b that is not bent from the front end 81 to the rear end 82 as shown in FIG. 6 may be used instead. In this case, the rectifying plate 8b is, as indicated by a straight line L6 parallel to the lower surface thereof,
The center point 40 of the developing roller 3 and the developing roller 3 of the rectifying plate 8b
By arranging so as to form an angle θ5 with respect to the straight line L7 connecting the closest portion 811 to the surface, the same effect as in the above embodiment can be obtained. In this case, in order to allow the developer from the agitator 6 to efficiently flow into the developer flow path 9, it is preferable to dispose the agitator 6 slightly below the illustrated position.

[0028]

According to the first aspect of the invention, the developer having passed through the developer flow path is located downstream of the developer carrying member in the rotation direction along the end of the developer rectifying member in the vicinity of the developer carrying member. Since it is guided and supplied to the developer carrying member, the developer does not stay in the vicinity of the developer flow path outlet even when the developer rectifying member applies an appropriate pressure to the developer to supply it to the developer carrying member. , The flow of the developer is stabilized by the rotation of the developer carrier,
As a result, the amount of developer supplied to the latent image carrier by the developer carrier can be kept constant, and stable and good developer supply performance can be obtained. According to the second aspect of the present invention, the developer remaining in the developer flow path at the time of non-development is released from the pressing state by the developer rectifying member and the developer supply member. The desired characteristics can be obtained only when it is necessary to apply an appropriate pressure, and the effect of not causing developer clogging in the developer channel or near the developer outlet of the developer channel during non-development is obtained. is there. According to the invention of claim 3,
Since an electric field whose strength changes at least periodically is formed between at least one of the developer rectifying member and the developer carrying member and between the developer rectifying member and the developer supplying member, the developer is At least one of the developer rectifying member and the developer carrying member or the developer rectifying member and the developer supplying member vibrates to increase fluidity. Therefore, there is an effect that the developer can be efficiently flowed without staying in the developer flow path, and the developer can be smoothly supplied to the developer carrier. Further, the developer is triboelectrically charged between the developer carrier and the developer supplying member, and as a result, the amount of charge of the developer can be increased, and a good image can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a developing device used in an electrophotographic copying machine according to an embodiment.

FIG. 2A is an explanatory diagram showing a state of the flow straightening plate when the developer flows in the developer flow path when the flow straightening plate is configured to be movable. FIG. 6B is an explanatory diagram showing a state of the straightening vane when the developer is not flowing in the developer flow path when the straightening vane is configured to be movable.

FIG. 3 is a schematic configuration diagram of an example in which a developer is vibrated among a developing roller, a supply roller, and a rectifying plate.

FIG. 4A is an explanatory diagram of a current plate according to another embodiment.
(B) is sectional drawing of the XX line arrow direction in (a).

FIG. 5 is an explanatory diagram of a supply roller according to another embodiment.

FIG. 6 is an explanatory view of a current plate according to another embodiment.

[Explanation of symbols]

 3 Developing Roller 4 Supply Roller 8 Straightening Plate 81 Front End 82 Rear End 83 Bend 9 Developer Channel 30 Developing Roller Power Supply 31 Supplying Roller Power Supply 32 Rectifying Plate Power Supply

Claims (3)

[Claims] 1. A developer carrier for supplying a developer to a latent image carrier on the surface of which a latent image is formed, a developer supply member for supplying a developer to the developer carrier, and the developer supply. A developer carrying device, comprising: a developer rectifying member that forms a developer flow path to the developer carrier at a portion facing the developer supply member and is opposed to the member at a distance. A developing device, characterized in that an end portion of the developer rectifying member in the vicinity of the body is configured to guide the developer to the downstream side in the rotation direction of the developer carrying body with the developer carrying body. 2. The developing device according to claim 1, wherein the developer rectifying member is configured so as to be separated from the developer supplying member so as to reduce the pressing force against the developer when not developing. . 3. A developer rectifying member, at least a portion in the vicinity of the developer carrying member is made of a conductor, and a predetermined gap is provided between the developer rectifying member, the developer carrying member and the developer supplying member. And at least one of the developer rectifying member and the developer carrying member, and at least one of the developer rectifying member and the developer supplying member have a cyclical strength. The developing device according to claim 1, wherein a voltage that forms a changing electric field is applied.